Allocation Planning Tool for DeterminingAllocation Planning Tool for Determiningthe Optimal Location and Sizing of Distributedthe Optimal Location and Sizing of Distributed

Generations in Provincial Electricity Authority ofGenerations in Provincial Electricity Authority ofThailandThailand

By Poonsak Saraisuwan

Department of Electrical Engineering, Chiang Mai University, Thailand

OutlineOutline

• Introduction• Problem formulation• DG allocation planning tool• Case studies and simulation

results• Conclusion

• Introduction• Problem formulation• DG allocation planning tool• Case studies and simulation

results• Conclusion

IntroductionIntroduction• Electrical energy consumption has

been increasing in every years.• This consumption must be met by

enlarging the capacity of generation,transmission, and distribution systems.

• Distributed generations (DG) offer thesolution to generation and distributionsystems constraints.

• The installation of DG units at non-appropriate location and sizing canresult in an increasing in power lossesor violations of system constraints.

100,000150,000200,000250,000300,000

2006 2007 2008 2009 2010 2011 2012 2013 2014 2015

GWh

Year

The forecast of electrical energy from 2006 - 2015

From : http://www.eppo.go.th

• Electrical energy consumption hasbeen increasing in every years.

• This consumption must be met byenlarging the capacity of generation,transmission, and distribution systems.

• Distributed generations (DG) offer thesolution to generation and distributionsystems constraints.

• The installation of DG units at non-appropriate location and sizing canresult in an increasing in power lossesor violations of system constraints.

DG

Reducing totalsystem power

lossesImproving power

transactions

From : http://www.eppo.go.th

Introduction (cont’)Introduction (cont’)

• Development of DG allocation planning tool for determiningthe optimal location and sizing of distributed generations

• Writing DIgSILENT Programming Language (DPL) scriptin DIgSILENT PowerFactory software.

• There are two objective functions subjected to practicalsystem constraints that can be selected by users.

• Daily load curve data are incorporated into the analysis tool.• Analytical results

– Output windows of PowerFactory– Microsoft Excel

• Development of DG allocation planning tool for determiningthe optimal location and sizing of distributed generations

• Writing DIgSILENT Programming Language (DPL) scriptin DIgSILENT PowerFactory software.

• There are two objective functions subjected to practicalsystem constraints that can be selected by users.

• Daily load curve data are incorporated into the analysis tool.• Analytical results

– Output windows of PowerFactory– Microsoft Excel

Problem FormulationProblem FormulationThe objective functions of DG allocation is formulated as aminimization of energy losses function or a maximization ofbenefit to cost ratio.

1. DGMin f EL Planning and recommendationby electric utilities

Using

2. BMax fC

Planning and recommendationby electric utilities

Using Investment planning byelectric utilities or investor-owned utilities

Selection

Problem Formulation (cont’)Problem Formulation (cont’)According to Provincial Electricity Authority (PEA) ofThailand regulations for DG connection1. System loading• composed of line and transformer loading

limit must be kept within 90 %

2. Voltage limit• Voltages limit at each bus must be stay

within 0.95-1.05 pu.

3. Reverse power• Total electric power generated by DG may

be larger than the total loads in the samedistribution system.

• The surplus power called reverse power• Reverse power flow back into the substation

is restricted by limiting DG capacity not toexceed power load on the system.

max

maxi i

i i

L L

TR TR

S S

S S

min maxi i iV V V

1. System loading• composed of line and transformer loading

limit must be kept within 90 %

2. Voltage limit• Voltages limit at each bus must be stay

within 0.95-1.05 pu.

3. Reverse power• Total electric power generated by DG may

be larger than the total loads in the samedistribution system.

• The surplus power called reverse power• Reverse power flow back into the substation

is restricted by limiting DG capacity not toexceed power load on the system.

min maxi i iV V V

0withDGlevelP

SingleBusbar(1)/B..

SingleBusbar/BB

Load

Line

Substation

DIgSILENT

+P

-P

4. Short circuit level• short circuit current limits at point of

common coupling, within 25 %• short circuit current interrupting

capacity limits due to DGconnection, within 85 %

5. Step voltage change• comparison of voltage at each bus

between prior and after DGconnection

6. Energy losses• comparison of total energy losses

between prior and after DGconnection

Problem Formulation (cont’)Problem Formulation (cont’)

, , /

, /

,

,

( )100

100

SC DG SC w oDG

SC w oDG

SC DG

SC rate

I IIPCC

II

ICI

, / ,

, /100

4% 4%

i w oDG i wDGi

i w oDG

i

V VVC x

VVC

4. Short circuit level• short circuit current limits at point of

common coupling, within 25 %• short circuit current interrupting

capacity limits due to DGconnection, within 85 %

5. Step voltage change• comparison of voltage at each bus

between prior and after DGconnection

6. Energy losses• comparison of total energy losses

between prior and after DGconnection

, / ,

, /100

4% 4%

i w oDG i wDGi

i w oDG

i

V VVC x

VVC

/

/100

2%

DG w oDG

w oDG

EL ELPELEL

PEL

Problem Formulation (cont’)Problem Formulation (cont’)

The exterior penalty function

max 2 max

min 2 min

min max

( )

( ) ( )

0i

i i i i

i i i i

i i i

x x if x x

h x x x if x x

if x x x

Penalty function

( ) ( ) ( ) ( ) ( ) ( ) ( )i i Sub i i iPE h V h S h P h IC h IPCC h VC h PEL

Total penalty function

1. DGMin f EL PE 2. B PEMax f

C

miniX

maxiX

DG allocation planning toolDG allocation planning tool

1. Input systems section- GIS- Create new project

2. Calculation engine- Writing DPL Script

3. Report section- DIgSILENT PowerFactory- Microsoft Excel

1

DG Planning ToolDG Planning Tool

1. Input systems section- GIS- Create new project

2. Calculation engine- Writing DPL Script

3. Report section- DIgSILENT PowerFactory- Microsoft Excel

2

3

The proposed DG Allocation AlgorithmThe proposed DG Allocation Algorithm

Input ParameterInput Parameter

DPL Script

Load flow calculationLoad flow calculation

kN

kt

kN

24 duration1

k

k

Nt hour

Daily Load CurveFlowchart of the time sweep function

Case studies and simulation resultsCase studies and simulation results

9-bus test system

SlackBus

Bus4

Bus1

Bus2

Bus3

Bus7

Bus6Bus5

Bus9

Bus8

ExternalGrid

Line

GeneralLoad

Line(1)GeneralL..

Line(2)Line(3)

General L..Load 7

General L..

GeneralL..

GeneralL..

General L..

Line(7)

Line(6)

Line(5)

Line(4)

DIgSILENT

Topic Result

The first objective functionLocationSizingThe comparison Energy losses

Bus 42.10 MW

Reduce 63.44 %

The second objective functionLocationSizingThe comparison Energy losses

Bus 33.25 MW

Reduce 56.29 %The sizing of DG is varied from 0.05 - 8 MW.

The first objective function values at all locationsand sizes of DG evaluated in one day

The results of the second objective function at alllocations and sizes of DG in 5 year

The sizing of DG is varied from 0.05 - 8 MW.

Minimum point Maximum point

The 437-bus of PEA distribution system whichis imported to PowerFactory

Case studies and simulation resultsCase studies and simulation resultsTopic Result

The first objective functionLocationSizingThe comparison Energy losses

NRB02N_2425.5 MW

Reduce 81.03 %

The second objective functionLocationSizingThe comparison Energy losses

NRB02N_1345.5 MW

Reduce 37.90 %

Results of the second objective function at theoptimal location with various sizes of DG

The 437-bus of PEA distribution system whichis imported to PowerFactory

Results of the first objective function and energylosses at the optimal location with various sizes of DG

ConclusionConclusion• The proposed DG allocation planning tool could be efficiently

and effectively used for determining the optimal location andsizing of DG.

• The planning tool can be used for practical distributionsystems.

• The planning tool considering both technical and economicconditions can reduce total energy losses under normal andpractically constrained conditions.

• The planning tool lead a higher efficiency level of powergeneration and distribution systems.

• The proposed DG allocation planning tool could be efficientlyand effectively used for determining the optimal location andsizing of DG.

• The planning tool can be used for practical distributionsystems.

• The planning tool considering both technical and economicconditions can reduce total energy losses under normal andpractically constrained conditions.

• The planning tool lead a higher efficiency level of powergeneration and distribution systems.

AcknowledgmentAcknowledgment

• Chiang Mai University• Provincial Electricity Authority of Thailand

Thank you forThank you foryour kind attentionyour kind attention